Wireless communications are important in modern society, and becoming more so all the time. Numerous people use wireless-communication devices in their personal lives and in their work lives as well. In the context of this disclosure, such wireless-communication devices are referred to as mobile radios, though it is explicitly noted that this term covers a wide variety of wireless-communication devices, such as cell phones, smart phones, tablet computers, laptop computers, and the like. Moreover, a given mobile radio could be associated with (e.g., mounted to) a given vehicle or a given user, as examples. Many mobile radios are also referred to as portable radios, in that they are designed and configured to be relatively easily carried from place to place by respective users. Some portable radios are designed and configured to be worn, perhaps detachably so, on or about a user's shoulder, chest, hip, and/or the like. Many portable radios are designed and configured to be carried about by users in their respective pockets, purses, handbags, backpacks, and the like. And certainly numerous other examples and example aspects of mobile radios could be listed here.
One context in which effective and reliable wireless communications are quite important is the public-safety context. In that context and in others, it is sometimes the case that radio channels that were originally designed to be allocable to one mobile radio at a time have been sub-divided into multiple channels that can be separately allocated to different mobile radios. In such an implementation, if a given radio channel has been sub-divided into two separately allocable, closely adjacent channels, it can occur that the uplink signal on a first one of those two channels is being received at a network base station at a power level that exceeds the power level at which the uplink signal on the second of those two channels is being received at the base station by such a degree as to block effective receipt by the base station of the uplink signal on the second channel. In such a scenario, from the perspective of a base station attempting to receive and decode the uplink signal on the second channel, the uplink signal on the first channel would often be referred to in the art as being “the blocking signal,” while the uplink signal on the second channel would often be referred to in the art as being “the desired channel.” Moreover, the uplink signal on the first channel would often be referred to in the art as being “the near signal,” while the uplink signal on the second channel would often be referred to in the art as being “the far signal,” though it is noted that these descriptors often but do not always accurately reflect actual relative distance from the receiving base station.
Moreover, although it is often the case that a desired signal can be properly obtained by applying a filter over a spectrum band that is centered on a center frequency of the desired signal and that is narrow enough in the frequency domain to limit the as-received power of the blocking signal enough to facilitate the obtaining of the desired signal, it can and does occur that the as-received power at the base station of the blocking signal exceeds the as-received power at the base station of the desired signal by such a degree as to preclude engineering a filter that would be both narrow enough to filter out a sufficient amount of energy from the blocking signal and wide enough to avoid degrading the ability to successfully obtain the desired signal.
For these reasons and others, there is a need for methods and systems for canceling a blocking signal to obtain a desired signal.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.
The apparatus and method components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.